Gas producing and consuming apparatus.



a.. n n

a SHEETS-SHEET 1.

Patented May 23, l911.

L. DOHERTY APPLIGATION FILED MAR. 16, 1908.

AS PRODUGING AND UONSUMING APPARATUS.

Patented May 23, }911.l

3 SHEETS-SHEET 2.

Sky H H. L. DOHERTY.'

GAS PRODUGING AND GONSUMING APPARATUS.

APPLICATION FILED MAR. 16, 1908.

H. L. DOHERTY. GAS PRODUCING AND GONSUMING APPARATUS.

AIPLICATION FILED MAR,1G 1908.

Patented May 23, 1911.

3 SHEETS-SHEET 8,

j nutren spares earner raton HENRY L. DOHERTY, OF NEW YORK, N. Y.

4GAS PRODUCING .AND CONSUMING APPARATUS.

Specification of Letters Patent.

Application filed March 16, 1908. SeralkNo. 421,503.

the following to be a full, clear, and exact.

description of the same, such will enable others skilled in the art to which it appertains yto make and usel the same.

My invention relates to gas producing and consuming apparatus, and particularly to apparatus comprising in combination a gas producer or furnace in which coal or other fuel is burned incompletely with resulting.-

production .of a combustible gas consisting largely of carbon monoxid, and air heating rccuperators wherein air for the draft current of the producer, and air for the combustion of the gas issuing from the producer, are heated initially by what is otherwisel vwaste heat.

ln another application,- filed March 1G, '1908, Sr. No.- 421,502, I have claimed certain features of construction" and arrangement of producer and recuperators embodied in the apparatus of my present \invcntion also, and therefore such features are not claimed herein.

My present invention relates to apparatus of the class referred to wherein water vapor is mingled with the air supplied to the producer, such water vapor reacting endotliermically with the carbon of the fuel, its

hydrogen .mingling with the carbon monoxid produced by the incomplete combustion of the carbon, and forming another combustible constituent of the gas produced. lily invention consists in improved means for utilizing waste heat in the heating of the air supplied to the apparatus, in irnproved means for evaporating water and mingling thc same with the draft current ofthe producer and superheating such water vapor, andin Vother features hereinafter set forth and particularly pointed out in the appended claims. v

The objects of my invention are to conserve as large a proportion as possible of the waste heat of the apparatus, to avoid the use of a separate steam generator, to mingle the water vapor and draft air thoroughly before the mixture reaches the producer, to utilize waste heat efficiently in thev evaporation of the water, to superheat the Water va- I por to a high degree, to raise the tem erature of the draft air, or primary air, to av high degree, to regulate eflicien'tly the tem-- perature in the producer, to insure a practically constant proportion of air and waterY vapor in the draft current, and to make the apparatus simple, compact, efficient, and readily Iadaptable to existingA apparatus of similar nature.

My. invention is susceptible of application to any producer or furnace where large quantities of high-temperature waste gases are available and where ypreheating of the air supply is desirable, but is particularly adaptable to combinations of a gas producer and gas-consuming furnace in which the two are functionally connected so that the gas from the producer is burned directly in the furnace as it is formed, and in which the products of combustion can bevintroduced at substantially the temperature at which they leave the furnace, into recuperators for preheating the air required for the producer and for the combustion ofthe gas, and for .the vapor-ization of the water used in the producer. f

As a particular application of my invention l have selected for illustration a furnace for heating retorts for the making of illuminating gas-such furnaces being commonly known as gas-benches. lccted this application of my invention for the reason that it furnishes ideal conditions for the operation of the invention; but thereA are a'great many other well known types of furnaces in connection with which my invention 1an be used with great advantage. For instance, it can be applied to gas producers `used in connection with zinc furnaces, reheating furnaces, ctc.

As set forth in my Patent No. 829,105, dated August Q1, 1906, in the-operation of a gas producer it is necessary to provide some means for keeping down the temperature of the fuel bed in the producer. rl"he reaction on which the formation of producer gas principally depends is that occurring when carbon is burned with a supply of air insufficient for complete combustion, namely, C fl-(XVIQCO. This is a highly exothermic reaction, 4450 B. T. U. being liberated for every pound of carbon burned. According to the process of my said prior patent, this excess of heat is absorbed by the endother- Patented May 23, 115ML have Se-.

' With carbon (CO2-#(12200) mic reaction involved in thereduction of carbon dioxid to carbon monoxid and the combination of'the liberated atom of oxygen Prior to such patented process, however, it Was the custom to absorb vthe excess heat by the vaporizationof Water and the dissociation of the elements of Water; and in some cases the use of Water as described to keep down the producer temperature is still preferred. As Water has commonly been used for such purpose heretofore, its use has been attended with great Waste of heat, due largely to the fact that the vapor-ization of the water htas been done either in a separate boiler` (requiring the combustion of fuel for the special purpose of vaporizing such Water), or by heat taken from the producer itself; as for eXa1npleby passing the entering draft current of air over a body of Water heated by the fuel bed in the producer, or by introducing air and Water into the ash pit of the producer, the Water beingl converted into steam by absorption of latentheat taken from the. fuel in the producer itself. There is broadly speaking, no loss of heat in the system due to dissociation of steam into its elements, the heat absorbed in dissociation being returned to the cycle in the subsequent recombination of the elements in the furnace. So far as the producer is concerned -therefore, there is no loss of heat due tithe introduction of steam into the producer save that required to heat the steam from the temperature at which it is4 introduced to'that at which the Waste gases leave the furnace; 'and thisloss is only serious wheuthe'ivater vapor or steam is supplied in such quantity and the temperature of the producer is so loW that a large proportion of vit goesthrough the producer undecomposed. But if the Water must be vaporized into steam by heat taken directly from the flu'el in a'bil'er, or inany other Way than by the utilization of other- Wise Wasted heat, a. considerable-loss, Which may be avoided by the means herein described, necessarily results.'

Ordinarily, in producers operating with aldraft current; of airand Water vapor or steamfthe air `has been supplied to the producer with little or noprevious heating. It is clear thatthe heat absorbed in heating this airup to the temperature atWhich the wast-e gases are discharged, is so much heat abstracted `from 'thatI which the producer ris capable f convertingi'nto useful poten'- tial heat in the'producer-gas. In the great majority ofcases where producer gas is applied to the heating' of furnaces, etc.; the products of combustion leave the apparatus ata temperature. yabove 1000 .F. Even Where recuperators are, employed to conserve 'part olfI this heat `carried lout of vthe furnace 'the temperatureaof the W'aste'g'ases 800" F., a loss of over 25000 B. T. U. more v or less per pound of carbon gasitied in the producer. Assuming that the Wastetnr tlue gases leave the furnace at a temperature of 1000 (which is a much lower teu'iperature than is gent-rally obtained even when regeucrators are used) there is a loss of sensible heat in the gases of 311-35 B. T. U. more or less. y the method and means herein described and illustrated, I utilize a large part of this heat of the waste gases to raise the temperature of the secondary air and also to raise the temperature of the primary air and to Vaporize water, the resulting steam being mixed with such primary air; and I am thus enabled to return to the producer the greater part of the waste heat in the products of combustion and thereby I- greatly increase the economi7 of operation and the efficiency of the apparatus. The vaporization of the water and heating up of incoming vdraft currents being no longer required to be done to any considerable degree by heat derived from the producer itself, a greater proportion of steam may be dissociated in the producer aud therefore a greater proportion of the heat generated in the producer is returned to the cycle by the subsequent recombination of hydrogen and oxygen in the furnace; also the caloric value of gas issuing from the producerv into the furnace is higher.

It is important to superheat the Water vapor to a high degree, to facilitate its decornposition in the producer; and also to mingle the Water vapor thoroughly with the air; and furthermore it is particularly desirable to conduct the evaporation of the Water in connection with the heating of the air and during the earlier stages of such heating, for during such evaporation the-conscquent absorption of latent heat keeps down the tem perature to a relatively low point,fso that there is a relatively great tempcratune-dif ference between the air and waste gases, the

latter already cooled considerably during' their passage through the upper sections of the recuperator, so that a relatively larger" proportion of contained heat is abstracted' from the waste gases than would be the -case if the evaporation Were done after they air had already been heated to a high degree. In other Words, byldoing the evaporation of the 'water by Waste gases which have aln4 ready parted with a large proportion vof their heat in superhcating the `Water vapor to a high degree and in heating the air to ra high degree, heat is 'utilized efficiently which would otherwise be relatively una` vailable, owing to the relatively low vtem- .peratur'e ofthe Waste gases.

` It is Obvious that there cannot be an efJ ticient interchange Iof heat between rela-'l tively cool. waste gases and a body of water4 perator with water-supply means, so that the air in passing through these passages itself evaporate's the water, taking up the water `vapor as fast as formed and so greatly facilitating the liberation of more vapor, and also keepingiithe air relatively cool and relatively moist in the early stages and so in a relatively goed condition to take up heat from the already partly-cooled waste gases. rhealosorption of the water vapor as fast as formed bythe air results in a particularly thorough admixture of\ the air and water vapor, which is particularly favorable `to efi'icient action of both in the fuel-bed of the producer.

in the accompanying drawings, showing one form of gas bench embodying my in- I vention, Figure 1 represents a vertical transverse section, looking from the front, on the line A B of Fig. 2. Fig. Q represents a longitudinal section on the-irregular section line C D of Fig. 1, the section being taken through one row of retorts and through the recuperator for the secondary air. Fig. 3 shows a central vertical section through the producer and furnace on the line E F of Fig. 1; and Fig. 4 shows a vertical longitudinal section on the irregular section line G H of Fig 1, the section being taken through 'the primary recuperator and vaporizer. Fig. 5 is a vertical section of an alternative form of secondary recnperator.

Ahe drawings represent simply a single -retort furnace or bench with its gas producer. in practice the benches are always built together in-groups or batteries, two

benches being placed bach to baclc forming atwin furnace or vbench setting. Any number of these'twin benches may be built together side by side.` For the purpose of illustrating my invention, however, it is suf-- cient to represent simply a vidual bench.

ln the drawings l1 designates the gas prosinrle indiducer having` a grate Q and charging chute This chute leads upward to thev retort l charging floor, which is indicated at 4. The

fuel', which may either be coal, or coke remaining front the distillation of the coal used in the reto'rts, is charged into the gas producer through 3 and is supported therein on the grate 2. In practicefa bed of ashes allowed to accumulate-on the grate to a considerable depth, .a bed of ignited fuel being built up exi-this. ,As is usual in producer practice, the depth of fuel bed is,'gener ally, considerable, since by using@ considand morel uniform quality is secured.

-The air for the partial combustion which takes place in the producer is admitted through the ports 5 under the grate 2, which ports communicate by passages or tlues 6 with the upperplongitudinal iiue 7 of the primary recuperator S. This primary recuperator comprises a series of tlues 7 within which are other fines (usually metal pipes) 1l through which a portion ofthe products ofv combustion from the furnace pass in esenters the lower-most of the fines 7 through thence passes upward through the various fines 7 and around the heating flues 11 each 'llue 7 next. above it, the connections being alternately in front and in rear, so that the lines '7 in principle form a return-bend passage for the air. The various heating pipes 11 are likewise connected in series so as to form in principle a return-bend heating coil. The uppermost of the fines' 7 is connected to the passages (3. In several of the lower lines T are water pans 13 provided with overflow connections 14, whereby when the water level in any pan rises above vthe level of such overflow connections the surplus passes through such overtiow connections,

beneath and so on until the lowest pan is reached. The overflow ,connections of this lowest pan connect with ay wastepipe 16. Tliese'pipes over which the water drips, may be provided on their under sides with transingendwise on them and so dropping mainly from one end or the other of the pipes. It is of course desirable that the fall of the water from the pipes shall be fairly uniform. 1ny case there is reason to believe that at times moisture communicated to the air during its passage through the tlues 7 by the evaporation of the water in said pans, may not be suliicient for the purpose desired, an 'auxiliary steam supplylinay be provided, for example, a steam pipe 17 opening into one of the tiues 7. The lowerniost ot lthe pipes 11 communicates with an oli'take tine 18 (Fig. Ll). The uppermost ,of the pipes 11 connects witha flue19, preferably of refractory material, 'havingports 20 leading into the furnace or main combustion chamber 21 within which arethe various retorts 22. The hoty combustion gases from this furnace 21 enter the flue 19 at or about Q00()o F., usually, and during their passage downward through the reeuperator 8 they give up a large part of their sensible heat to the entering air current surround- `the reverse of the downward flow of these products of combustion. Suclreiiternig air erable depth of fuel a gas of much better a suitable damper or register 10 (Fig. 4) and I liuc 7 circept the lastbe'ing connected to the over the heating pipe 11 below to the pan4 vers ribs to prevent the water from travelv i ing them andiiowing upward in a directionv caping. to the stack. The air to be heated iso - up by the air current; all the water carried by th air current beingl therefore converted into steam highly superheated by the time the air has passed through. outlet 5 into the ash-pit. By these two methods of absorbing and utilizing the waste heat` of the portion of the products of combustion passing through recnperator S, a very large port-ion of available heat of such waste gases is utilized. It will be apparent that not only will the water vapor be mixed most thoroughly with the primary air-.but that the proportion of water vapor to air will be practically constant so long` as the feed of water or steam to the conipartmeins of the priimlry recup'eratoi"isI constant; also, that the proportioil of water vapor to the all' may be varied within wide limits; by sup-, plying water to more or less of the :pans 1?. in this w'ay the proportion of, water to airl may bc aried so that the` steam is highly superheated after leaving the reeuperator, or that the air is merely saturatedv` o r that it carries a large excess of water. rlhereby the temperature in the producer may be regulated as desired.

The secondary recnperator t), upon the opposite side of the furnace. comprises. in its upper part, ftues 28 pre'lerablyof' refractory material and, in its lower part, pipes 24, preferably of metal, these (lues and pipes connected in series so as to constitute in principle a return-bend coil` as clearly shown in Fig. 2. These flues 23 and Qt are located, in a vertical tlue 25 to the lower portion of which air is admitted through a perforated grate or damper QG as indicated yin FigQ, the various flues 2-l and 24; being supported one above the other upon cross pieces 2T so that the air so entering and passing upward through the tlue 9 passes over and around the fiues Q3 and, 24 in a direction which is in general the reverse of the direction of How of the products of combustion through the recupeator, and thence passes through lues 28 and nostrils 29 into the combustible gas rising from producer l, causing the combustion of such gas within chamber 21 and around the retort's 22, one part of the resulting products of combustion passing out through recuperatorB and the other part outward through recuperator 9, as previously described.

The connection of two recuperators in parallel (to borrow an electrical term) instead of in series (21.6., the primary recuperator taking the products of combustion after they have passed through the secondary recuperator) has the important advantage that, since the products of combustion enter the primary reeuperator at practically the temperatureof the furnace, they are hot enough to heatl the primary air to an effective. degree as welly as to evaporate a large amount of moisture; whereas the products of combustion after leaving the secondary recuperator have been lowered in temperature so much (and would be lowered in temperature so much even if all the products of combustion were passed through the secondary recuperator) that they are too cold to heat the primary air effectively and to vaporize the desired amount of mois' ture.

The lower sections of the secondary rceuperator are of metal in order to permit as e'tlicient transfer ofheat through their Walls as possible; the upper sections of this rccu perator being shown as made of refractory material, this being practically necessary tion otthe recuperator. The temperature in the primary recuperator being more moderate owing to the presence of water vapor, all or most of the Sections of this recuperator may be made of metal except thc uppermost draft current is led otf to the ash-pit. I provide dampers 30 (Fig. 4) and 31 (Fig.

4aybetiween the primary and secondary recupeI -ators respectively.` and the otftake flue i8, to provide for regulable distribut-ion of the relative amounts of product-s of combustion passing through the two recuperators.

i In Fig. 5 I illustrate a secondary recuperlator alternative to that. shown in Fig. 2 and in which both thc air and the products of combustion pass in '/.ig zag course through the rta-operator as in Fig. 2, the products of nected at the end by tees 33, and the air passes upward through zig zag flues 34 within which the tlues 32 are located. In the construction shown plates 35 (usually of iron) are interposed in alternate joints between tees 83, to force the, products ofcombastion to pass in tortuous course to the ofl'take 18.

Most gas benches in use at the present day eitherhave only seconder y recuperators or, if provided with both pri-.nary and secowing to the high temperature in this por` section-the section above Where the heated` ondary recuperators, the primary recuper-v combustion pass through return lues 32 conv ven direct fromthe retort oven. But it is relatively easy to reconstruct such existing gasl benches by providing a primary recuperator on one side of the producer and a secondary recuperator on the other side of the pro ducer, as herein illustrated and described, and in such case the Waste gases are received in the primary recuperator at substantially the temperature at Which they leave the retort oven and hence at a temperature such that they can evaporate moisture and superheat Water vapor and heat the primary air efficiently.

It has been proposed heretofore to pass the primary air and the secondary air through separate recnperators, heated by separate currents of Waste gases, and then to pass the heated primary air over Water contained in the ashpit beneath the producer, in order that such air may take up Water vapor to give the required endothermic action in the producer. It is obvious, however, that t-he economy of such an apparatus cannot be as great as that of an apparatus of equally good design in which the water is brought into contact with the primary air in the [irse or lower-temperature passages of the primary recuperator, because in the prior proposed apparatus referred to, owing to the low specific heat of dry air and to there being no absorption of heat by evaporation ot Water, the temperature of the primary air rises much more rapid-ly in the first portion of the primary recuperator than when water is being evaporated inthat portion of the recuperator, and so the exchange of heat between the waste gases and the primary air is less elicient, and the primary air issuing from the primary recuperator carries with it a lower prop ation of heat units. Furthermore, in the prior proposed apparatus referred to, the heated primary air entering the ash pit will necessarily be greatly lowered in temperature the result of absorption of latent heat in evaporating the water in the ash pit, so that the draft current of air and water 'vapor will eneounter'the fuel in the producer at a lower temperature and with a lower degree of superneat of the water vapor, (or possibly without any superheat of the water vapor,) than when the water vapor is supplied-to the primary air in the firstportion of the primary recuperator, according to my invention. The relatively low teml'ierature of the primary air, and the relatiiely low superheat, or even absence cf super-heat, of the water vapor, are both unfavorable tothe production of a high proportion of ca'rbn monoXid, and occasion Waste of heat in heating up the air and Iwater vapor to the temperature of the fuel. AFurthermore, when there is a-pool of water in the ash pit it is inevitable that such vattr will abstract considerable heat from the fuel bed above-a source of Waste which is avoided by introducing the water into the recuperator instead of into the ash pit.

By introducing the water into the earlyv stages of the primary recuperator am not only able to abstract `a greater portion of the heat of the Waste gases, and to avoid unnecessary abstraction of'heat from the fuel bed by the water, but the Water vapor so introduced into the primary draft current is superheated to a high degree before it leaves the primary recuperator, and so both the primary air and the water 'apor in the primary air reach the fuel already heated to a temperature approximating' that'of the fuel-a condition verv favorable to the conversion of a relatively .large proportion of the fuel into carbon monoxid. l `urthermore, the relatively low temperatures in the earlier sections of the primary recupcrator permit the walls which separate the primary air from the lwaste gases to be of metal-a material of high heat conductivity; for which reason the interchange-ot' heat between the outgoing` waste gases and the entering primary air is particularly eilicient.

ln a divisional ap}` lication, filed L\rpril 2l, 1911, Sr. No. (522,542),.1 claim the process carried out by the abovedescribed apparatus.

lrVhat l claim is l. A combined gas producer and furnace, comprising a gas producer, a furnace chamber arragi-ied to receive gas therefrom, and primary and secondary recuperators each comprising separate passages for air and for products of combustion, and arranged to receive separate currents of products of combastion from said furnace chamber, said primary `recuperator provided with a succession of open water receptacles in its air passage arranged to overflow one into another.

2. The combination of a furnace and a recuperator therefor comprising separate passages for air and waste gases and a succession of open water receptacles in such air passage arranged to overflow one into another.

3. A combined gas producer and furnace, comprising a gas producer, a furnace chamber arranged to receive gas :trom said producer, and primary and secondary recuperators, both connected to said furnace chamber and arranged each to receive its separate current of products of combustion from vsuch chamber. the primary recuperator comprising separate return-bend passages for the products of combustion and for entering air, arranged one within another and located in the wall of the producer, and comprising also means for supplying moisture. to thc air passing therethrough, said primary recuperator connected to the lower part of the producer, the secondary recuperator having separate passages for the products of combustion and for the secondary air current, and arranged 4to deliver the secondary air into the gas issuprising separate passages for the products of v combustion and for entering air, and comprising also Ameans for supplying moisture to the air passing therethrough, the secondary recuperator comprising two flue-passages, for air and products of combustion respectively, one such passage located within the other and composed of sections, certain of which are composed of material of relatively high heat conductivity and others of which are composed of refractory material.

5. A combined gas producer and furnace comprising a gas producer, a furnace chamber arranged to receive gas from said producer', and primary and secondary recuperators, both connected to said furnace chambc: and arranged each to receive its separate currentof products of combustion from such chamber, the primary recuperator comprising separate tine-passages for the products of combustion and for entering air respecperators, both connected to said furnace chamber and arranged each to receive its separate current of products of combustion from such chamber'1 the primary recuperator comprising separate flue-passages for the products of combustion and for entering air respectively, located one within another, the

inner flue passage composed of a plurality of return-bend sections, the outerA flue pas?. sage comprising a plurahty of water pansv arr: ngcd one above another and alternated by the sections of the inner flue passage, said pans provided with overflow connections arranged to discharge overflow water uponr the sections of the inner Aliue passage immediately beneath and thence over the surface of such sections to the pans beneath. A In testimony whereof I altiX my signature in the presence of two witnesses.

HENRY L. DOHERTY. lVitnesses Gro. S. PEARsoN, FRANK lV. rlmJANoFF.4 

